Test swab device and method of detecting lead, mercury, arsenic, and bismuth

ABSTRACT

A swab is impregnated with a test reagent such that a test for a specific substance can be effected by rubbing the impregnated swab over the surface to be tested and then viewing the swab for a reagent reaction. A method for testing for a substance includes impregnating a swab with a reagent, and rubbing the swab over a surface suspected of containing the substance. If the substance is present in the surface, a reaction with the substance produces an easily detectable color on the swab tip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/709,981, filed on Jun. 4, 1991, now abandoned, which was acontinuation of application Ser. No. 07/499,488, filed May 7, 1990, nowU.S. Pat. No. 5,039,618, which was a continuation-in-part of applicationSer. No. 07/305,221, filed on Feb. 2, 1989, now abandoned.

TECHNICAL FIELD

The present invention relates to a swab and a method of using the swabin a test for certain chemical elements, and more particularly, thepresent invention relates to a swab for retaining test reagents, amethod of using the same in a test for metals or other specific elementsor compounds, and a method of making the same.

BACKGROUND OF THE INVENTION

Contamination of the environment has been increasing steadily for yearsas the use of metals, chemicals, pesticides, and bacterial organisms hasincreased. Even though the toxicity of various metals has been known forcenturies, it is only recently that there has been a serious increase ininterest in minimizing human exposure to such metals. Current publicawareness of such pollutants and their associated hazards has created aconsumer demand for products that are capable of determining thepresence of unwanted and potentially dangerous materials.

Some of the more toxic metals include lead, cadmium, mercury, barium,chromium and beryllium. Lead, in particular, has been subject to muchattention due to its presence in articles or paints commonly found inthe home. See, for example, "A Simple Direct Estimation ofUltramicroquantities of Lead in Drinking Water Using Sodium Rhodizonate"by E. Jungreis and M. Nechama, Microchemical Journal, vol. 34, pp.219-221 (1986); U.K. Patent Application No. 2 025 047 A; "A SimplifiedMethod for Detection of Lead Contamination of Soil" by J. Preer and G.Murchison, Jr., Environmental Polution (Series B), vol. 12, pp. 1-13;and "A Spot Test for Detection of Lead in Paint" by J. Sayre and D.Wilson, J. Pediatrics, vol. 46, pp. 783-785 (1970).

As the titles of some of the prior art publications indicate, there is arecognized need in the industry for a simple or simplified test ormethod for determining the presence of lead. However, as will becomeapparent from the remaining descriptions of the prior art, prior to thepresent invention, an effective and simple test for lead had not beendeveloped.

In a popular prior art method of detecting lead in paint, sodium sulfide(Na₂ S) is reacted with lead to form lead sulfide (PbS), a blackprecipitate. The presence of lead is thus confirmed by the appearance ofthe black precipitate, lead sulfide. This method has severaldisadvantages: (1) the sodium sulfide is potentially toxic, especiallyto young children; (2) the black precipitate is difficult to see on darksurfaces; (3) the sodium which has a noxious odor; and (4) the reagentsreact sulfide releases volatile hydrogen sulfide (H₂ S), with manycations to form black precipitates and thus tends to give false readingson many metallic surfaces.

Another common analytical reagent is a metal complexing agent,rhodizonic acid. For over forty years, rhodizonic acid and salts thereofhave been used as analytical reagents to detect heavy metals, includinglead, in both qualitative and quantitative analyses. The methodology forusing rhodizonate dye is based on two types of tests:

(1) a quantitative determination of heavy metals in solutions using aspectrophotometer to obtain quantitative information; and

(2) qualitative determinations which use filter papers impregnated withthe reagent.

In addition, semi-quantitative information can be derived from the useof columns packed with silica gel impregnated with rhodizonate dye. SeeU.K. Patent Application No. 2 025 047 A.

The Macherey-Nagel Company (Duren, Federal Republic of Germany)manufactures a test paper for the determination of lead under thetrademark PLUMBTESMO. The PLUMBTESMO strips comprise a heavy filterpaper with a reagent impregnated therein. To test for lead in asolution, a strip is dipped into the solution, and observed for a colorchange that indicates the presence of lead. The PLUMBTESMO strips canalso be used to detect lead deposits in motor vehicle tailpipes.

The instruction sheet that is distributed with the PLUMBTESMO stripsindicates that the PLUMBTESMO strips may be used to detect the presenceof lead on a degreased surface. However, the instruction sheetimplicitly recognizes that the PLUMBTESMO strips are not entirelysatisfactory for testing for the presence of lead on a surface.Specifically, the instruction sheet indicates that the PLUMBTESMO stripmay have to be held firmly against a test surface for as long as fifteenminutes before an indication of lead develops. Clearly, fornonprofessional, household use, a test strip that must be held firmlyfor fifteen minutes is entirely unsatisfactory in that many users willbecome impatient after only a few minutes and will discontinue theapplication of the PLUMBTESMO strip against the test surface. That typeof usage may, of course, result in dangerous false readings, leaving theuser with the erroneous impression that lead is not present when in factlead may be present.

A further disadvantage of the PLUMBTESMO strips is that the testoperator must directly handle the test strips, thus being unnecessarilyexposed to chemicals. Yet another disadvantage of the PLUMBTESMO stripsis that the strips are flat and comparatively stiff, and are thus notreadily conformable to curved or otherwise unusually contoured surfaces,such as those that one is likely to encounter on moldings in olderhouses.

Thus, it should be clear that the lead tests, known prior to the presentinvention, are not entirely satisfactory.

Although not a test for lead, U.S. Pat. No. 4,707,450 discloses abiological specimen collection and test unit. The teachings of U.S. Pat.No. 4,707,450 are quite different from the present invention. Insummary, U.S. Pat. No. 4,707,450 discloses a specimen collection devicethat utilizes a swab to collect biological specimens for testing afterthe swab has been removed from the specimen collection location. Sincelead and other metals do not readily collect on a swab when rubbed on ametal-containing surface, the disclosed swab is not useful for testingfor metals. This is especially true because the success of the disclosedswab depends upon the removal of a specimen from the collection site forsubsequent testing. Because metals will not usually collect on the swab,the swab will not work well for metals testing.

Thus, there is a need in the art for a test or method for determiningthe presence of toxic metals, such as lead and cadmium. While leadtoxicity is better known, cadmium is toxic by inhalation of dust or fumeand is a carcinogen. Cadmium plating of food and beverage containers hasled to outbreaks of gastroenteritis or food poisoning. Other metals arejust as toxic. Thus, a simple test for metals and other toxic substanceswould serve to protect consumers from the toxic effects caused thereby.

SUMMARY OF THE INVENTION

Briefly described, the present invention relates to a swab that isimpregnated with a test reagent such that a test for a specificsubstance can be effected by rubbing the impregnated swab over thesurface to be tested and then viewing the swab for a reagent reaction.

The present invention also relates to a device for testing for asubstance on a surface including a cartridge, two compartments withinsaid cartridge containing a reagent and an activating solution,respectively, and an absorbent ball of material mounted on at least oneend of the cartridge. The reagent and activating solution are combinedand mixed within the cartridge before the device is used.

The invention also relates to a method of making a device for testing asubstance on a surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may more easily be understood by reference to thedrawings, wherein:

FIG. 1 is a view in cross section of a swab according to the presentinvention prior to the insertion of a reagent.

FIG. 2 is a view in cross section of a swab according to the presentinvention with a reagent inserted therein.

FIG. 3 is a view in cross section of a cartridge swab according to thepresent invention containing a cartridge and loose powder.

FIG. 4 is a view in cross section of a cartridge swab according to thepresent invention containing buffer and a cartridge containing dye.

FIG. 5 is a view in cross section of a cartridge swab according to thepresent invention containing two cartridges side by side.

FIG. 6 is a view in cross section of a cartridge swab according to thepresent invention containing two cartridges end to end.

FIG. 7 is a view in cross section of a dual swab according to thepresent invention with a reagent inserted therein.

FIG. 8 is a view in cross section of a cartridge with a dual swabaccording to the present invention containing a cartridge and loosepowder.

FIG. 9 is a view in cross section of a cartridge with a dual swabaccording to the present invention containing buffer and a cartridgecontaining dye.

FIG. 10 is a view in cross section of a cartridge with a dual swabaccording to present invention containing two cartridges side by side.

FIG. 11 is a view in cross section of a cartridge with a dual swabaccording to the present invention containing two cartridges end to end.

FIGS. 12 and 13 are views of embodiments of the present invention usingmicroencapsulation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The test swabs of the present invention may be used to detect a varietyof substances on a variety of surfaces depending on the reagentcontained in the swab, including but not limited to, paint, ceramics,dust, soil, plantleaves, solder, bird cages, etc. The test swabs may beused to determine the presence of lead, cadmium, bismuth, mercury,cobalt, arsenic, tin, antimony, iron, aluminum, selenium, copper ororganophosphates, among others. The present invention preferably will beused to determine the presence of metals in such surfaces.

The swabs can be made in a variety of formats as shown in the Figures,described below.

Referring now in detail to the drawings, wherein like reference numeralsrefer to like elements throughout, in the embodiments of FIGS. 1 and 2,a swab is indicated generally by reference numeral 10. The swab 10includes a stem 12 that is preferably formed from a hollow tube. Thestem 12 may bemade from glass, plastic, or any other suitable material.If plastic is used, the composition of the plastic is not critical.However, because glass is breakable and because plastic is more easilycrimped, plastic is preferable to glass.

In an alternative embodiment of the present invention, a solid stem maybe used.

At one end of the stem 12, a ball 14 of absorbent material is affixed.The absorbent material may be comprised of any number of materials,including,but not limited to: cotton fibers, rayon fibers, dacronfibers, monofilament polyester, monofilament nylon, other fibrouspolymeric compositions, or an open cell structure such as polyurethanefoam. Table Ilists several commercially available swabs, together withthe source or manufacture of each swab.

                  TABLE I                                                         ______________________________________                                                 APPROX-                                                              ABSOR-   IMATE                STICK                                           BENT     DIAM-     STICK      DIAM-                                           MATERIAL ETER      MATERIAL   ETER   SOURCE                                   ______________________________________                                        Cotton   0.25"     Plastic    3/16"  J&J                                      Cotton   0.25"     Wood Solid        CitMed                                   Cotton   0.50"     Wood Solid        CitMed                                   Rayon    0.25"     Plastic    3/16"  CitMed                                   Rayon    0.50"     Plastic    5/16"  CitMed                                   Dacron   0.25"     Plastic    3/16"  CitMed                                   Nylon                                Coventry                                 Polyester                                                                              0.25"     Plastic    3/16"  Coventry                                 Polyester/                           Coventry                                 cellulose                                                                     Polyurethane                         Coventry                                 Porous                               Plastic                                  Plastic                              Interflo                                 Foam dauber                          Metal                                                                         Super                                                                         Brush Co.                                Wool dauber                                                                            0.75"                       Metal Nat'l                                                                   Novelty                                                                       Brush Co.                                ______________________________________                                    

For purpose of testing for lead, the preferred reagent dye is rhodizonicacid. Table II lists various dyes that are acceptable, together with thesupplier or manufacturer of each.

                  TABLE II                                                        ______________________________________                                        DYE                   SUPPLIER                                                ______________________________________                                        Rhodizonic acid, potassium salt                                                                     Sigma Chemical                                                                Company                                                 Rhodizonic acid, sodium salt                                                                        Sigma Chemical                                                                Company                                                 Rhodizonic acid, disodium salt                                                                      Sigma Chemical                                                                Company                                                 Rhodizonic acid, disodium salt                                                                      Eastman Kodak                                                                 Company                                                 ______________________________________                                    

No major difference in purity or other analytical criteria were reportedfor similar salts. The above materials all function well in testing forthe presence of lead, as indicated below. An activator solution,describedbelow, typically will be used with the reagent dyes in carryingout embodiments of the present invention.

For purposes of testing for cadmium, the preferred reagent dyes are4-nitronaphthalenediazoamino-azo-benzene or1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine. The latter dye may beobtained from Aldrich as Cadion.

Other substances may be tested for using the reagents and activatingsolutions listed in Table III.

                  TABLE III                                                       ______________________________________                                                Dye (Reagent                                                                  which Reacts   Activating                                             Metal   with Metal     Solution      Color                                    ______________________________________                                        Bi      Cinchonine - KI                                                                              Dilute acid   Orange                                           (1%)                         Red                                      Hg      1)    Diphenylcar- 0.2M HNO.sub.3                                                                            Violet                                               bazide (1% in                                                                 alcohol)                                                                2)    Cobalt (II)  Cobalt (II) Deep                                                 thiocyanate test                                                                           acetate     blue                                   Sb      1)    Rhodamine B  Sb.sup.+5   Blue                                                 (Tetraethyl- nitrite                                                          rhodamine)                                                              2)    Phosphomolyb-                                                                              Sb.sup.+3   Blue                                                 dic acid                                                        Fe      1)    2,2'-bipyri- Thioglycolic                                                                              Red                                                  dine or 1,1' acid bufer                                                       phenanthro-                                                                   line                                                                    2)    3-(2-pyridyl)-                                                                             1,2,4-triazine,                                                                           Purple                                               5, 6-bis(4-  sodium salt                                                      phenyl-                                                                       sulfonic acid)                                                  Al      1)    Aurin        NaOH        Red                                                  tricarboxylic                                                                 acid                                                                    2)    Quinolizarin Ammonia, then                                                                             Red                                                               glacial HONC                                       Se      Pyrrole reagent                                                                              0.5M iron (III)                                                                             Green-                                                          chloride; H.sub.3 PO4                                                                       Blue                                     organo- Phosphomolybdic                                                                              1)    K.sub.2 SO.sub.8 +                                                                      Blue                                   phos-   acid formed with     K.sub.2 SO.sub.4                                 phates  sodium molybdate                                                                             2)    Ascorbic                                                                      Acid                                             Cu      1)    Quinolyl     20 g Na acetate                                                                           Red                                                  reagent (0.2 g/l                                                                           10 g K Na                                                        in amyl alcohol)                                                                           tartrate                                                                      3 g hydroxyl-                                                                 ammonium Cl                                                                   (all in 100 ml                                                                H.sub.2)O                                                  2)    Dithiooxamide            Dark-                                                (1% in acetone)          Green                                                (Rubeanic acid)                                                 Co      Rubeanic acid  Ammonia/alkali                                                                              Brown                                                           tartrates                                              As      Magnesium      Silver nitrate                                                                              Red                                              nitrate/ammonium                                                              chloride                                                              Sn      Sodium sulfide dilute acid   Brown                                                                         (Sn.sup.+2)/                                                                  Yellow                                                                        (Sn.sup.+4)                              ______________________________________                                    

Several granular and particulate solids were tried as diluents orfillers for the dyes to be used in the swabs. While fillers are notrequired, theyare useful to provide bulk to the dye when the dye is asolid so the dye can be placed in the swabs more conveniently since thedye is used in a small amount. No filler is needed when the dye to beused is a liquid. Thefiller material may be any material which does notadversely affect the desired reaction. All of the materials listed inTable IV can be used as afiller for the dyes used in the test method ofthe present invention, but some exhibited more desirable properties thanothers. The more granular and less sticky solids are preferable to usewith automatic filling equipment, such as a Kinematics Powder FillingMachine, model no. 1700 equipped with a model 3015 filling gun.

Table IV identifies several fillers and their ease of use with automaticfilling equipment.

                  TABLE IV                                                        ______________________________________                                        FILLER          RECOMMENDATION                                                ______________________________________                                        Alumina, acid   Worked well with the machine                                                  and filling gun.                                              Talc            Worked well with the machine                                                  and filling gun.                                              Silicic acid    Formed a plug, but worked                                                     with the machine and filling                                                  gun.                                                          Glass beads     Formed a plug, but worked                                                     with the machine and filling                                                  gun.                                                          Polyvinylpyrrolidone                                                                          Not recommended for use with                                                  the filling equipment.                                        ______________________________________                                    

The rhodizonate dye is unstable in an aqueous medium. As a result,hygroscopic fillers may retain moisture too avidly and will consequentlycontribute to inactivation of this dye.

Table V identifies several materials capable of use as a filler for thedye, together with comments concerning the suitability of each material.

                  TABLE V                                                         ______________________________________                                                     APPEAR-                                                          BULKING AGENT                                                                              ANCE        COMMENTS                                             ______________________________________                                        Alumina                                                                       WB-2, basic  Loose, sandy                                                                              Mixes well;                                          hygroscopic,             fills tube easily.                                   WA-1, acidic Loose       Mixes well; hygroscopic,                                                      fills tube easily.                                   WN-3, neutral                                                                              Loose       Mixes well; hygroscopic,                                                      fills tube easily.                                   Bentonite                Particulate                                                                   Colored powder;                                                               unsuitable for use.                                  Cellulose                                                                     SigmaCell 20 Loose       Mixes well; fills tube                                                        easily.                                              SigmaCell 50 Loose       Mixes well; fills tube                                                        easily.                                              Florisil     Granular    Mixes poorly with dye;                                                        fills tube easily.                                   Fuller's Earth           Large Pieces                                                                  Particles too large to                                                        use.                                                 Fumed Silica Fluffy      Too fluffy; mixes                                                             poorly; hard to use for                                                       filling.                                             Glass Beads  Sandy       Mixes with dye poorly;                                                        fills tube easily.                                   Gum acacia   Loose       Mixes well; fills tube                                                        easily.                                              Mannitol     Clumpy      Hygroscopic, dye mixes                                                        well.                                                Polyvinylpyrrolidone     Granular; mixes poorly;                              (PVP)                    unsuitable for filling                                                        machine.                                             Silicic acid Loose       Dye does not mix well;                                                        fills tube easily.                                   Starch                                                                        Potato*      Loose       Mixes well; turns dark;                                                       does not fill easily.                                Wheat        Loose       Mixes well; does not                                                          fill tube easily.                                    Talc         Powder      Mixes with dye                                                                moderately well; fills                                                        tube easily.                                         Zeolite      Fluffy Powder                                                                             Turns blue with the dye.                             Zeolite mixture                                                                            Fluffy Powder                                                                             Turns blue with the dye.                             ______________________________________                                        *Potato starch is susceptible to oxidation, and turns black on reaction        with iodine. Rhodizonate reacts with potato starch as iodine does.       

Accordingly, alumina (all types), talc, gum acacia, silicic acid, andmannitol are all suitable materials for use as a diluent with the dye.However, other materials in accordance with the spirit of the presentinvention may be used.

The swabs 10 are filled through the open end 16 of the stem 12,preferably with automatic filling equipment, such as that describedabove. Once the desired quantity of dye and filler 20 is inserted intothe swab 10, the end 16 of the stem 12 may be crimped as shown at 18 inFIG. 2. In the embodiment of FIG. 7, a ball of absorbent material 14 isinserted after the swab 10 is filled to provide a dual swab system.

In another embodiment, the swabs are filled with a dye/filler mixtureusinga Kinematics dispensing machine to fill. Then, the solid filledswabs are shaken on a vibrating table to disperse the solid throughoutthe swab. A four inch wooden applicator is inserted into the swab toprevent loss of reagent through the open end and a drop of glue from aglue gun then is applied to the end of the unit. In the dual swabembodiment of FIG. 7, an absorbent ball is added to the end of the swab.

Automatic filling units can be designed by using a metal brace notchedwiththe appropriate size holes to ensure that the swabs remain in afixed position during an automatic filling operation. A conveyor beltcan move these units under a fixed dispensing gun. After the dispensingof the solid reagent, the swabs can be sealed by a variety of automaticprocedures including, melting to close, using pressure to close andflattening the plastic handle of the swab.

In various tests, swabs were filled with 20, 30, 40, and 80 mg. of thedye and filler. In such tests, the ratios of filler to dye were variedbetween0 and 100:1.

In use, the absorbent ball 14 of the filled swab 10 is wetted with anactivator solution. A pH level of between about 2.0 and about 3.0 ispreferable for the lead-rhodizonate reaction. For the lead reaction, abuffer generally is used as the activator solution. A pH level of 2.8for the buffer is optimal for the lead-rhodizonate reaction. The wettedabsorbent ball 14 is then rubbed onto a surface suspected of containinglead. If lead is present on the surface, a reaction occurs with therhodizonate dye, thus causing an easily detectable deep pink color toappear on the absorbent ball 14 of the swab 10. The test is evensensitiveenough to detect lead dust on a surface caused by sandinglead-containing paint, even after the surface had been vacuumed andwashed with trisodium phosphate detergent.

For the cadmium reaction, the activator solution generally will comprisesodium tartrate, sodium acetate, sodium titrate, potassium hydroxide ora mixture thereof. Additional chelating materials such as EDTA may alsobe present. The pH preferably used for the cadmium reaction is aboveabout 8,more preferably above 9. The potassium hydroxide may be used toadjust the pH. Bases other than hydroxide, which form insoluble cadmiumcomplexes, such as carbonate, might be used. When testing for cadmium,the area to betested is rubbed with the swab containing the reagent andactivator solution. If the swab becomes pink, cadmium is present.

The pH to be used with detection of other metals and substances will bereadily determined by one of ordinary skill in the art from the reagentsand activating solutions disclosed in Table III and the Examples below.

INTERFERENCES CAUSED BY OTHER CATIONS

Many cations form complexes with rhodizonate. However, the specificconditions for optimal reaction of most cations are different from thoserequired for lead. Only barium and lead form a red or deep pink complexunder the conditions defined for the swab tests. The color formed by thereaction with barium is red-brown and thus to a skilled technician isdistinguishable from the color formed during the reaction with lead.However, to avoid confusion, the reaction with barium can bedistinguishedfrom the reaction with lead with the use of sodium sulfide.A drop of sodium sulfide (7.5%) on top of the developed pink swabchanges the swab to black in the presence of lead by forming leadsulfide. The precipitate formed by the reaction between sodium sulfideand barium is not black, i.e., sodium sulfide does not change to blackin the presence of barium alone.

The solid fill method, described above with the use of a Kinematicsfillingmachine, is the manufacturing option that is best for preservingthe stability of the dye reagent. However, alternative manufacturingprotocolsare also available.

In an alternative method of preparation of a swab for a lead test, anaqueous solution of 0.01 M rhodizonate (dye) is prepared. Therhodizonate solution may be prepared using a tartrate buffer at pH 2.8.Although that pH level is the preferred level for the lead testingreaction, at that pH level, the rhodizonate dye is unstable andcompletely degrades in about thirty-six hours. As an alternative, therhodizonate solution can be prepared using water at pH 5 or 6. At thatpH level, complete degradation of the rhodizonate takes about ninety-sixhours.

The addition of some organic solvents may enhance the stability of theaqueous rhodizonate solution. For example, 10 to 20% methanol, ethanol,oracetone may be added.

Within one hour of preparation of the solution, swabs are dipped in thesolution for thirty seconds to one minute. The swabs are then rapidlyfrozen in acetone/dry ice, or liquid nitrogen, and dried bylyophilization. The swabs can then be used in the same manner as theswabsthat are filled from the inside with a filling machine. The swabscan alternatively be dried under heat, although the temperature must bekept below 80° C.

In another embodiment, the swabs can be pretreated by soaking theabsorbentmaterial of the swabs in a tartrate buffer, pH 2.8, or anyother buffer with a pH preferably between 2 and 3. The soaked swabs arethen dried under heat.

Since other cations might interfere with a test for lead, the swab canalsobe presoaked in a buffer containing EDTA for about one minute inorder to clean other possible interfering cations from the swab prior tothe test. The EDTA can be included in the buffer described in thepreceding paragraph.

In one preferred embodiment, the swab of the present invention isprepared as a cartridge swab. In this embodiment, a device for testingfor a substance or metal on a surface comprises a cartridge, at leasttwo compartments within the cartridge wherein one compartment contains areagent that reacts with the metal and the other compartment contains anactivating solution, and an absorbent ball of material mounted at leastone end of the cartridge. The reagent and activating solution arecombinedand mixed within the cartridge before the device is used. Thisembodiment can take several forms, some of which are shown in FIGS. 3-6and 8-11.

The simplest design of the cartridge swab is a system wherein twocompartments are used. One compartment contains an activator solutionand the other contains a dye. When testing for lead, the activatorsolution will be the buffer solution described above and the dye will berhodizonate dye. When testing for cadmium, the activator solution willbe sodium tartrate, sodium acetate, sodium titrate, potassium hydroxideor mixtures thereof, and the dye will be4-nitronaphthalene-diazoaminoazo-benzene or1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine. The absorbent ballmounted at one end of the cartridge swab may be attached when thecartridge swab is prepared or it may be attached when the cartridge swabis to be used. Where there is an absorbent ball at each end of thecartridge swab, one end is closed with an absorbent ball, the cartridgeswab is filled and then the other absorbent ball is attached when thecartridge swab is prepared or when it is to be used.

FIG. 3 shows an embodiment of a cartridge swab wherein a breakablecartridge 22 contains a small amount of activator solution. Thebreakable cartridge 22 is inserted into a plastic holder or cartridge 24into which dry dye powder 26 plus any additives required for the testdesired has been dispensed. The swab tip 14 generally will be placed onthe cartridge 24 before the cartridge 24 is filled with dry dye powder26 and the breakable cartridge 22. When the cartridge swab is to beused, the breakable cartridge 22 is broken and the activator solutionmixes with thedye powder and wets the swab tip. The swab tip then can berubbed over the surface to be tested. As shown in FIG. 8, thisembodiment may also be utilized in the dual swab configuration.

FIG. 4 shows an embodiment of a cartridge swab wherein a small breakablecartridge 28 is prepared containing dry dye powder plus any additivesrequired for the desired test. The cartridge 28 is placed inside anotherbreakable cartridge 32 large enough to hold cartridge 28 and sufficientactivating solution 34 to execute the desired test. The breakablecartridge is broken when the test is to be performed and the activatingsolution mixes with the dye and wets the swab tip which can be rubbedoverthe surface to be tested. As shown in FIG. 9, this embodiment mayalso be utilized in the dual swab configuration.

FIG. 5 shows an embodiment of the cartridge swab wherein two breakablecartridges are used side by side in a larger cartridge. Breakablecartridges 36 and 38 will contain either activating solution or dye. Thecartridges are broken together when the test is to be performed and theactivating solution mixes with the dye and wets the swab tip which canbe rubbed over the surface to be tested. As shown in FIG. 10, thisembodimentmay also be utilized in the dual swab configuration.

FIG. 6 shows an embodiment of the cartridge swab wherein two breakablecartridges 36 and 38 are used in an end to end format inside a largercartridge 40 which has a swab tip 14. The cartridges are broken togetherwhen the test is to be performed and the activating solution mixes withthe dye and wets the swab tip which can be rubbed over the surface to betested. As shown in FIG. 11, this embodiment may also be utilized in thedual swab configuration.

In the dual swab embodiments of FIG. 8-11, the compartments must containenough reagent and activating solution to wet the absorbent balls ateach end of the cartridge swab. This may require using an additionalamount of each reagent in the cartridges over the amount needed for themonoswab embodiments. One of ordinary skill in the art will readily beable to ascertain the amounts needed for a dual swab cartridge from theexamples below for the monoswab embodiments.

In a further embodiment, more than two compartments are provided toallow the necessary amount of reagent and activating solution to bepresent in the cartridge swab. For example, four cartridges may be usedto supply thenecessary reagent and activating solution to each end ofthe cartridge swab.

In a further embodiment of the present invention, only one end of thecartridge is closed with an absorbent ball and the other end of thecartridge is closed with abrasive paper or board material. Thisembodimentis preferred for use on surfaces which need to be toughened inorder to getgood contact between the absorbent ball and the surface. Thecartridge swabcan be used to first roughen the surface with the abrasivepaper, and then test the surface for a substance or metal with the endof the cartridge swab having an absorbent ball.

The swab tips on the cartridge swabs can be the same type of swabsdescribed above for use on the stick type swabs.

The cartridges which are used to hold the breakable cartridgescontaining the reactants for the desired test can be nonbreakable orsqueezable containers. For example, a squeezable cartridge similar to atoothpaste tube may be used. The breakable cartridges are placed insidethe squeezable cartridge and the end is closed with a fibrous or porousswab tip. The swab tip optionally may have a pointed tip which breaksthe cartridges contained within the tube. The squeezable cartridge issqueezed, breaking the cartridges within the squeezable cartridge andmixing the reagents. The reagents wet the swab tip which can then berubbed over the surface to be tested.

The breakable or squeezable cartridges contained within the cartridgeswabsmay be glass, plastic or other material which will open uponcrushing or squeezing. Where glass cartridges are used, the unit willpreferably contain spacers between the cartridges to prevent prematurebreakage of the glass cartridges, allowing reagents to mix prior to thedesired time for use. When plastic cartridges are used, any type ofplastic which will open on application of pressure is satisfactory. Thisplastic may be rigidand brittle, such as butyrate tubing, polymethylpentene or polystyrene or flexible, such as low density polyethylene,polyallomer, or polyvinyl chloride. Flexible plastic containers areadvantageous since there is no glass to break and no pieces of glasswhich may come through the outer package. Such flexible plasticcartridges may be sealed using an ultrasonic sealing technique so thatgentle pressure will break the seals opening the reagent cartridges,releasing the materials contained inside.

The test swabs are preferably packaged in test kit packets which includeatleast one and, more preferably, several swabs. For test kits for lead,the test kit will preferably also contain a control tube filled withsodium sulfide. As discussed above, sodium sulfide reacts with manycations to form black precipitates and may give false readings when usedas a test for lead. However, it has been found useful to include acontrol tube containing sodium sulfide in the test kits for lead inorder to enable theuser of the test kit to double check the results ofthe other test swabs. The inclusion of a sodium sulfide control may alsobe useful where the user desires to test for lead on plaster and stuccosurfaces. Since these materials may contain sulfates, the reagents usedin the test swabs according to the present invention may be blocked fromreacting with lead in the plaster or stucco surface to produce a visiblereaction. The sodiumsulfide tube is provided to allow the user to checkthese surfaces with thesame kit as used for other surfaces.

In one preferred embodiment, the test kit will contain an insert cardwhichhas been coated in at least one area with a lead or othermetal-containing material. For example, a cardboard or paper boardinsert may be prepared with one or more circles or patches of lead orother metal-containing material coated thereon. If a user of the testkit obtains negative results with the test swabs in the kit when theswabs are applied to the surface of interest, the user can rub the swabsover the areas of metal-containing material on the insert card to verifythe accuracy of thetest. If the swabs indicate the presence of lead orother metal when contacted with the card containing such material, theuser is assured thatthe negative results obtained were correct.

The test kit according to the present invention comprises at least onedevice for testing for a substance on a surface, comprising a cartridge,at least two compartments within the cartridge wherein at least onecompartment contains a reagent that reacts with the substance and atleastone other compartment contains an activating solution, and anabsorbent ball of material mounted at at least one end of the cartridge.The reagentand activating solution are then combined and mixed withinthe cartridge before the device is used.

In a preferred embodiment, the test kit further comprises at least onetubefor dispensing sodium sulfide. The tube for dispensing sodiumsulfide may be any type of tube or dropper for dispensing materials.Preferably, the tube will be a test swab according to the presentinvention.

In a preferred embodiment, the test kit further comprises an insert cardcoated in one or more areas with the substance for which the kit isintended to test. The insert card may by cardboard, paper board or anyother material capable of being coated with the desired material.

As an alternative to the embodiments using one or two cartridges, therecanbe a plurality of compartments containing reagents. In oneembodiment, the compartments are micro-compartments such as those formedby microencapsulation. The micro-compartments can be formed by anymethod known to those of skill in the art of microencapsulation. SeeFIG. 12.

FIG. 13 illustrates another embodiment utilizing microencapsulationhaving a liquid layer 42, a solid layer 44, and a liquid permeableabsorbent pad,46. In a further embodiment, the liquid layer and thesolid layer may be reversed.

The following examples are provided to further illustrate the invention,but are not meant to limit the scope of the invention in any way.

EXAMPLES Tests to Determine Preferred Ratios or filler to Dye EXAMPLES ITHROUGH XIII

In examples I through XIII, swabs were obtained from CitMed having anabsorbent ball of 0.50 inch diameter made from rayon fibers. The swabstemwas a 3/16 inch hollow plastic tube. Alumina (WA-1, acidic) was usedas an inert diluent, and rhodizonate dye, disodium salt (from the SigmaChemicalCompany) was used as the dye. The inert diluent was mixed withthe dye in the ratios set forth in Table V. Table V also lists thequantity of fill used in the swab, together with the test results.

In performing the above examples, the swabs, after being filled with theabove-designated quantities of the above-designated ratios of filler anddye, were wetted with 1.5 ml. of 0.2M tartrate buffer, pH 2.8. The swabswere then rubbed on wood that had been previously painted with 0.5%lead-containing paint. In most instances, a positive reaction wasclearly visible within seconds, almost always within less than oneminute. A positive reaction is indicated by a deep pink color appearingon the absorbent ball of the swab.

                  TABLE VI                                                        ______________________________________                                        RATIO                                                                         ALUMINA:DYE  FILL (mg)   REACTIVITY                                           ______________________________________                                        100:1        40          All positive                                         100:1        80          All positive                                         80:1         40          All positive                                         80:1         80          All positive                                         60:1         40          All positive                                         60:1         80          All positive                                         40:1         30          All positive                                         40:1         40          All positive                                         40:1         80          All positive                                         20:1         40          All positive                                         20:1         80          All positive                                         10:1         40          50% positive-too much                                                         dye                                                   5:1         40          no reaction-too much                                                          dye                                                  ______________________________________                                    

EXAMPLE XIV

A mixture of alumina (acidic) and rhodizonate dye, sodium salt at aratio of 40:1 was suspended in 0.2M tartrate buffer, pH 2.8. Thefollowing swabs: cotton, 6" plastic rod, from CitMed; rayon, 6" plasticrod, from CitMed; and dacron, 6" plastic rod, from CitMed, wereindividually dipped in the suspension. The dipped swabs were then rubbedon a piece of wood painted with a 0.5% lead-containing paint. Thesuspension lost activity rapidly, losing its ability to detect leadwithin one minute. It is interesting to note that the suspension lostactivity more rapidly when soaked onto the swab, as in this example,than when the mixture was filledthrough the center of the swab and thenwetted with the buffer.

EXAMPLE XV

A mixture of alumina (acidic) and rhodizonate dye, sodium salt at aratio of 20:1 was suspended in 0.2M tartrate buffer, pH 2.8. Thefollowing swabs: cotton, 6" plastic rod, from CitMed; rayon, 6" plasticrod, from CitMed; and dacron, 6" plastic rod, from CitMed, wereindividually dipped in the suspension. The dipped swabs were then rubbedon a piece of wood painted with a 0.5% lead-containing paint. Thesuspension decayed at a rate slower than the suspension used in exampleXIV. Activity was still observed after five minutes.

EXAMPLE XVI

A mixture of mannitol and rhodizonate dye, sodium salt at a ratio of20:1 was suspended in 0.2M tartrate buffer, pH 2.8. The following swabs:cotton, 6" plastic rod, from CitMed; rayon, 6" plastic rod, from CitMed;and dacron, 6" plastic rod, from CitMed, were individually dipped in thesuspension. The dipped swabs were then rubbed on a piece of wood paintedwith a 0.5% lead-containing paint. The suspension decayed at a rateslowerthan the suspension used in example XIV. Activity was stillobserved after five minutes.

Tests to Determine Sensitivity of Reagent EXAMPLE XVII

To determine the sensitivity of the test, a contoured wood molding stripwas divided into ten different sections. Each section was painted withlatex paint that was mixed with a different quantity of lead, rangingfrom0.1% to 1.0%. The following diagram illustrates the various ratiosused:

    0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8% 0.9% 1.0%

A swab with a 0.5 inch diameter absorbent ball made from rayon fibersand a5/16 inch hollow plastic stem was filled with 40 mg. of alumina(WA-1, acidic) and rhodizonate dye, disodium salt (from the SigmaChemical Company) in a 40:1 ratio. A 1.5 ml. solution of 0.2M tartratebuffer, pH 2.8 was used as the developing agent. Within less than thirtyseconds, a deep red color developed on the swab after rubbing thetreated swab on thewood section painted with 0.4% lead-containing paint.Similarly treated swabs had equal or better results on all sections ofthe wood having a higher percentage of lead in the paint.

Tests to Compare Results of Swab With Results of Filter Paper EXAMPLEXVIII

For comparison with the swab test set forth in example XVII above, asimilar test was conducted using Whatman 3 mm. filter paper. A solutionwas prepared using 40 mg. of alumina (WA-1, acidic) and rhodizonate dye,disodium salt (from the Sigma Chemical Company) in a 40:1 ratio and a1.5 ml. solution of 0.2M tartrate buffer, pH 2.8. The filter paper wasdipped into the solution, allowing the solution to completely saturatethe filterpaper. The saturated filter paper was then promptly rubbedover the wood painted with lead-containing paint.

The filter papers never clearly turned pink even when used on thesections of wood having high concentrations of lead. Hints of pink wereoccasionally visible at the edges of the filter paper; however,interpretation was very difficult. The wood underneath the filter paperdid become pink, but this pink color was only visible on the lightcoloredpaint, not on the dark paint. On the contoured wood surfaces itwas difficult to make good contact between the filter paper and thecontoured surfaces.

EXAMPLE XIX

A swab with a 0.5 inch diameter absorbent ball made from rayon fibersand a5/16 inch hollow plastic stem was filled with 40 mg. of alumina(WA-1, acidic) and rhodizonate dye, disodium salt (from the SigmaChemical Company) in a 40:1 ratio. A 1.5 ml. solution of 0.2M tartratebuffer, pH 2.8 was used as the developing agent, i.e., the swab wasprepared exactly as set forth in example XVII, above. This time the swabwas rubbed on lead-glazed ceramic dishes. Within less than thirtyseconds, the tip of the swab was obviously pink.

EXAMPLE XX

A solution was prepared using 40 mg. of alumina (WA-1, acidic) andrhodizonate dye, disodium salt (from the Sigma Chemical Company) in a40:1ratio and a 1.5 ml. solution of 0.2M tartrate buffer, pH 2.8. Apiece of Whatman 3 mm. filter paper was dipped into the solution,allowing the solution to completely saturate the filter paper, i.e., thefilter paper was prepared in accordance with the method set forth abovein example XVIII. The treated filter paper was rubbed on the lead-glazedceramic dishes used in example XIX. No detectable color was observed onthe filterpaper after several minutes of contact with the lead-glazeddishes.

EXAMPLE XXI

Plain untreated swabs having a rayon fiber absorbent ball of 0.5 inchdiameter on a 5/16 inch hollow plastic stem were soaked in a solution of40 mg. of alumina (WA-1, acidic) and rhodizonate dye, disodium salt(from the Sigma Chemical Company) in a 40:1 ratio and a 1.5 ml. solutionof 0.2Mtartrate buffer, pH 2.8, i.e., the same solution used in examplesXVIII andXX. When the swabs were then rubbed on the lead-glazed ceramicdishes, a clear positive result was easy to read.

EXAMPLE XXII

Plain untreated swabs having a rayon fiber absorbent ball of 0.5 inchdiameter on a 5/16 inch hollow plastic stem were soaked in a solution of40 mg. of alumina (WA-1, acidic) and rhodizonate dye, disodium salt(from the Sigma Chemical Company) in a 40:1 ratio and a 1.5 ml. solutionof 0.2Mtartrate buffer, pH 2.8, i.e., the same solution used in

examples XVIII, XX, and XXI. When the swabs were then rubbed on the woodpainted with at least 0.4% lead-containing paint, a clear positiveresult was easy to read.

From the results of examples XVII through XXII, it is clear that theswab is far superior to the filter paper for effecting a test for thepresence of lead using rhodizonate dye.

Comparison of Different Types of Swabs EXAMPLE XXIII

A mixture of alumina (acidic) and rhodizonate dye, sodium salt at aratio of 40:1 was filled into the following swabs: cotton, 6" plasticrod, from CitMed; rayon, 6" plastic rod, from CitMed; and dacron, 6"plastic rod, from CitMed. About 3/16" to 1/4" of material was filled ineach swab. The swabs were then wetted with tartrate, sodium salt andrubbed on a wood board painted with a 0.5% lead-containing paint.

There were no notable differences in color intensity among the swabsmade of cotton, rayon, or dacron. The dacron and rayon swabs wettedwell, whereas the first few drops of buffer beaded on the surface of thecotton.During the rubbing stage, the dacron swab did not hold up as wellas the cotton and rayon swabs.

EXAMPLE XXIV

A mixture of mannitol and rhodizonate dye, sodium salt at a ratio of20:1 was suspended in 0.2M tartrate buffer, pH 2.8. The following swabs:cotton, 6" plastic rod, from CitMed; rayon, 6" plastic rod, from CitMed;dacron, 6" plastic rod, from CitMed; molded foam from Coventry Mfg. Co.;spun foam from Coventry Mfg. Co.; and 3" cotton tipped swabs fromJohnson & Johnson, were individually dipped in the suspension. Thedipped swabs were then rubbed on a piece of wood painted with a 0.5%lead-containing paint. The foam materials did not wet well, and littleor no color formation was observed on the material or the wood. Thecotton, rayon, anddacron swabs had intense color on the fibers. Under amicroscope it appeared that the fibers had been dyed. It did not appearas though a precipitate had been formed and trapped by the fibers.However, at high concentrations of lead and dye, some precipitate mayform. The precipitateis not necessary in order to detect a reaction.

The size of the absorbent ball on the swab also had little apparenteffect on the test results.

EXAMPLE XXV

A swab with a hollow stem is filled with 30 mg of a mixture of4-nitronaphthalene-diazoaminoazo-benzene and an inert filler, alumina inratios as shown in Table VI. The swab tip is wetted with an activatorsolution containing sodium potassium tartrate, sodium acetate, or sodiumcitrate at pH 8.5. The area to be tested is rubbed with the swab. Ifcadmium is present, the swab becomes pink.

EXAMPLE XXVI

One crushable cartridge is filled with 30 mg Cadion,(1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine) and talc. Anotherbreakable cartridge is filled with 0.5 ml activator solution which is amixture of sodium tartrate, sodium acetate and sodium hydroxide. The pHofthe activator solution is adjusted to be basic at a pH greater than 9.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes pink if cadmium is present.

Tests for Other Materials EXAMPLE XXVII

A swab with a hollow stem is filled with 30 rag of a mixture ofcinchonine-potassium iodide reagent and an inert filler such as aluminainratios as shown in Table VI. The swab tip is wetted with an activatorsolution containing dilute acid such as 0.1M HNO₃ at pH 2-3. The areatobe tested is rubbed with the swab. If bismuth is present, the swabturnsorange-red.

Although the salts of lead, copper and mercury react with iodide andhence interfere with the reaction with bismuth, bismuth can be detectedin the presence of these metal salts.

EXAMPLE XXVIII

One breakable compartment is filled with 30 mg of cinchonine-potassiumiodide and an inert filler such as talc. Another breakable compartmentis filled with 0.5 ml of activator solution containing dilute acid suchas 0.1 N HNO₃ adjusted to pH 2.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the compartments are broken open andthe unit is shaken to ensure good mixing. The swab tip is rubbed overthe areato be tested and becomes orange-red if bismuth is present.

Although the salts of lead, copper and mercury react with iodide andhence interfere with the reaction with bismuth, bismuth can be detectedin the presence of these metal salts.

EXAMPLE XXIX

A swab with a hollow stem is filled with 30 mg of a mixture of diphenylcarbazide and an inert filler such as alumina in ratios as shown inTable VI. The swab tip is wetted with an activator solution containing0.2 M HNO₃ in 6% ethanol. The area to be tested is rubbed with the swab.Ifmercury (Hg⁺²) is present, the swab turns violet.

EXAMPLE XXX

One crushable cartridge is filled with 30 mg of a mixture of diphenylcarbazide and an inert filler such as talc. Another breakable cartridgeisfilled with 0.5 ml of activator solution containing 0.2 N HNO₃ in 6%ethanol. The two cartridges are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes violet if mercury (Hg⁺²)is present.

EXAMPLE XXXI

A swab with a hollow stem is filled with 30 mg of a mixture of ammoniumthiocyanate, cobalt (II) acetate and an inert filler such as alumina inratios as shown in Table VI. The swab tip is wetted with water. The areato be tested is rubbed with the swab. If mercury (Hg⁺²) is present, theswab turns deep blue.

EXAMPLE XXXII

One crushable cartridge is filled with 30 mg of ammonium thiocyanate,cobalt (II), and an inert filler such as talc. Another breakablecartridgeis filled with 0.5 ml of activator solution containing aneutral buffer or water.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes deep blue if mercury (Hg⁺²) ispresent.

EXAMPLE XXXIII

A swab with a hollow stem is filled with 30 mg of a mixture of RhodamineB (tetraethylrhodamine) and sodium nitrite (as an oxidizing agent) andan inert filler such as alumina in ratios as shown in Table VI. The swabtip is wetted with an activated solution containing 15% potassiumchloride in 2M HCl. The area to be tested is rubbed with the swab. Ifantimony as the chloroantimonate ion (SbCl₆ ⁻) is present, the swabturns violet or blue.

EXAMPLE XXXIV

One crushable cartridge is filled with 30 mg of Rhodamine B(tetraethylrhodamine) and sodium nitrite (as an oxidizing agent) and aninert filler such as talc. Another breakable cartridge is filled with0.5 ml of activator solution containing 15% potassium chloride in 2MHCl. The two cartridges are placed inside a larger cartridge having aswab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the areato be tested and becomes violet or blue if antimonyas the chloroantimonateion (SbCl₆ ⁻) is present.

EXAMPLE XXXV

A swab with a hollow stem is filled with 30 mg of a mixture ofphosphomolybdic acid and an inert filler such as alumina in ratios asshown in Table VI. The swab tip is wetted with an activator solutioncontaining dilute acid such as 0.1N HCl. The area to be tested is rubbedwith the swab. The tip of the swab is held over steam for a few minutes.If antimony (Sb⁺³) is present, the swab turns blue.

EXAMPLE XXXVI

One crushable cartridge is filled with 30 mg of phosphomolybdic acid andaninert filler such as talc. Another breakable cartridge is filled with0.5 ml of activator solution containing dilute acid such as 0.1N HCl.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and then held over a stream of steam for a fewminutes. If antimony (Sb⁺³) is present, the swab turns blue.

EXAMPLE XXXVII

A swab with a hollow stem is filled with 30 mg of a mixture of 2,240-bipyridine and an inert filler such as alumina in ratios as shown inTable VI. The swab tip is wetted with an activator solution containing0.1M HCl and hydroxylamine hydrochloride as reducing agent (pH 2). Thearea to be tested is rubbed with the swab. If iron (II) ion is present,the swab turns pink or red. Reducing agent hydroxylamine hydrochlorideis added to the activating solution to reduce ferric ions (Fe⁺³) toferrous ions (Fe⁺²).

EXAMPLE XXXVIII

one crushable cartridge is filled with 30 mg of 2,2'-bipyridine and aninert filler such as talc. Another breakable cartridge is filled with0.5 ml of activator solution containing 0.1 HCl and hydroxylaminehydrochloride as reducing agent (pH The two cartridges are placed insidealarger cartridge having a swab tip at one end. When ready to use, thebreakable cartridges are broken and the unit is shaken to ensure goodmixing. The swab tip is rubbed over the area to be tested and becomespinkor red if iron (II) ion is present.

Reducing agent hydroxylamine hydrochloride is added to the activatingsolution to reduce ferric ions (Fe⁺³) to ferrous ions (Fe⁺²).

EXAMPLE XXXIX

A single crushable cartridge is filled with 0.5 ml activator solutioncontaining 0.1N HCl and hydroxylamine hydrochloride (pH 2). The swab tipis impregnated with 2,2'-bipyridine by wetting the tip with a solutionof 2,2'-bipyridine in ethanol and allowing the tip to dry.

The single cartridge is placed inside a larger cartridge having the swabtip at one end. When ready to use, the breakable cartridge is broken andthe unit is squeezed gently to wet the swab tip. The swab tip is rubbedover the area to be tested and becomes pink or red if iron (II) ion ispresent.

EXAMPLE XL

A swab with a hollow stem is filled with 30 mg of a mixture ofo-phenanthroline and an inert filler such as alumina in ratios as showninTable VI The swab tip is wetted with an activator solution containing0.1M HCl and hydroxylamine hydrochloride as reducing agent (pH 2). Thearea to be tested is rubbed with the swab. If iron (II) ion is present,the swab turns pink or red.

Reducing agent hydroxylamine hydrochloride is added to the activatingsolution to reduce ferric ions (Fe⁺³) to ferrous ions (Fe⁺²).

EXAMPLE XLI

One crushable cartridge is filled with 30 mg of o-phenanthroline and aninert filler such as talc. Another breakable cartridge is filled with0.5 ml of activator solution containing 0.1M HCl and hydroxylaminehydrochloride as reducing agent (pH Reducing agent hydroxylaminehydrochloride is added to the activating solution to reduce ferric ions(Fe⁺³) to ferrous ions (Fe⁺²).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes pink or red if iron (II) ion ispresent.

EXAMPLE XLII

A single crushable cartridge is filled with 0.5 ml activator solutioncontaining 0.1N HCl and hydroxylamine hydrochloride (pH 2). The swab tipis impregnated with o-phenanthroline by wetting the tip with a solutionofo-phenanthroline in water and allowing the tip to dry.

The single cartridge is placed inside a larger cartridge having the swabtip at one end. When ready to use, the breakable cartridge is broken andthe unit is squeezed gently to wet the swab tip. The swab tip is rubbedover the area to be tested and becomes pink or red if iron (II) ion ispresent.

EXAMPLE XLIII

A swab with a hollow stem is filled with 30 mg of a mixture of the ironspecific reagent, 3-(2-pyridyl)-5,6-bis(4-phenylsulfonicacid)-1,2,4-triazine monosodium salt, and an inert filler such asalumina in a ratio as shown in Table VI. The swab tip is wetted with anactivator solution containing water or dilute acid (0.1N HCl) orthioglycolic bufferand hydroxylamine hydrochloride as reducing reagentat pH 2. The area to betested is rubbed with the swab. If iron (II) ispresent, the swab turns purple.

EXAMPLE XLIV

One crushable cartridge is filled with 30 mg of the iron specificreagent 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazinemonosodium salt, and an inert filler such as talc. Another breakablecartridge is filled with 0.5 ml of activator solution containing wateror dilute acid (0.1N HCl) or thioglycolic buffer and hydroxylaminehydrochloride as reducing reagent at pH 2.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes purple if iron (II) ion is present.

EXAMPLE XLV

A swab with a hollow stem is filled with 30 mg of a mixture of aurinetricarboxylic acid and an inert filler such as silica in ratios as shownin Table VI. The swab tip is wetted with an activator solutioncontaining dilute NaOH. The area to be tested is rubbed with the swab.If aluminum ion (Al⁺³) is present, the swab turns red.

EXAMPLE XLVI

One crushable cartridge is filled with 30 mg of a mixture of aurinetricarboxylic acid and an inert filler such as silica. Another breakablecartridge is filled with 0.5 ml of activator solution containing diluteNaOH.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes red if aluminum (Al⁺³) is present.

EXAMPLE XLVII

A swab tip is impregnated with the quinalizarin reagent by first soakingthe tip in a solution containing quinalizarin and then allowing the tiptoair dry. Prior to use, the swab tip is wetted with a solution ofammonium hydroxide. The area to be tested is rubbed with the swab. Theswab tip is then developed by first exposing the tip to ammonia vaporsand then to glacial acetic acid vapors. If aluminum ion (Al⁺³) ispresent, the swab tip turns red to red-violet.

The quinalizarin reagent is prepared by dissolving 10 mg quinalizarin in2 ml pyridine and diluting with 18 ml acetone.

EXAMPLE XLVIII

A swab tip is impregnated with the quinalizarin reagent by first soakingthe tip in a solution containing quinalizarin and then allowing the tiptoair dry. One crushable cartridge (labelled A) is filled with 0.3 ml ofconcentrated ammonia solution. Another breakable cartridge (labelled B)isfilled with 0.3 ml of glacial acetic acid.

The two cartridges are placed inside a larger cartridge having thequinalizarin impregnated swab tip at one end. When ready to use, thecrushable cartridge (A) containing the ammonia is broken first and theunit is gently squeezed to wet the swab tip. The swab tip is rubbed overthe area to be tested. Then the second cartridge (B) containing theglacial acetic acid is broken and the unit is gently squeezed to wet thetip with the acid. If aluminum ion (Al⁺³) is present, the swab tipdevelops a red to red-violet color.

The quinalizarin reagent is prepared by dissolving 10 mg quinalizarin in2 ml pyridine and diluting with 18 ml acetone.

EXAMPLE XLIX

A swab with a hollow stem is filled with 30 mg of a mixture of iron(III) chloride and an inert filler such as alumina in ratios as shown inTable VI. The swab tip is first wetted with a solution containing dilutephosphoric acid adjusted to pH 4-5. The area to be tested is rubbed withthe swab. Then approximately 5 drops of syrupy phosphoric acid isapplied to the swab tip and allowed to soak in. Finally 2-3 drops of adeveloper solution containing 1% pyrrole in aldehyde-free ethanol isapplied to the swab tip. If selenium (Se⁺²) is present, the swab turnsgreenish-blue.

EXAMPLE L

One crushable cartridge labelled A is filled with 0.5 ml solution of 0.5M iron (III) chloride in dilute phosphoric acid (0.1M). Anotherbreakable cartridge labelled B is filled with 0.5 ml of developingreagent which consists of 1% pyrrole reagent in aldehyde-free ethanol. Asmall, separatedropper filled with concentrated phosphoric acid (sp. gr.1.75) is also provided.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridge (labelled A)nearest the swab tip is broken first and the unit is gently squeezed towet the swab tip. The swab tip is rubbed over the area to be tested.Then 4-5 drops of concentrated phosphoric acid (contained in dropper) isapplied to the swab tip and allowed to soak in. The second breakablecartridge (labeled B) containing the developer solution is broken andthe unit is gently squeezed to allow the developer solution to soakthrough the swab tip. If the swab tip becomes greenish blue, thenselenium ion (Se⁺²) or selenites are present.

EXAMPLE LI

A swab with a hollow stem is filled with 30 mg of a mixture of rubeanicacid (or dithiooxamide) and an inert filler such as alumina in ratios asshown in Table VI. The swab tip is wetted with an activator solutioncontaining ammoniacal alkali tartrates at a pH greater than 9. The areatobe tested is rubbed with the swab. If copper (Cu⁺²) is present, theswab turns black or greenish black. Nickel and cobalt ions also reactwithrubeanic acid under similar conditions to form blue and brownprecipitates or colors, respectively.

EXAMPLE LII

One crushable cartridge is filled with (1) 30 mg of a mixture ofrubeanic acid (dithiooxamide) and an inert filler such as alumina ortalc. Another breakable cartridge is filled with 0.5 ml of activatorsolution containingammonia and alkali tartrates at a pH greater than 9.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes black to greenish black if copper ions(Cu⁺²) are present. Nickel and cobalt ions also react with rubeanic acidunder similar conditions to form blue and brown precipitates or color,respectively.

EXAMPLE LIII

A swab with a hollow stem is filled with 30 mg of a mixture of2,2'-biquinoline-4,4'-dicarboxylic acid or 2,2'-biquinoline (cupron) andan inert filler such as alumina in ratios as shown in Table VI. The swabtip is first wetted with 0.5 ml amyl alcohol to solubilize the cupronintothe swab. The swab tip is then wetted with approximately 1 ml of anactivator solution at pH 2 (see below). The area to be tested is rubbedwith the swab. If copper ions (Cu⁺²) are present, the swab turns purpleor red.

The activator solution is prepared by dissolving 20 g sodium acetate, 10g potassiumsodium tartrates and 3 g hydroxylammonium chloride in 100 mlwater. The pH is adjusted to 2 with HCl.

EXAMPLE LIV

One crushable cartridge is filled with 0.5 ml of a solution of2,2'-biquinoline-4,4'-dicarboxylic acid or 2,2'-biquinoline (cupron) inamyl alcohol (0.2 g/l). Another breakable cartridge is filled with 0.5ml of activator solution (see below) adjusted to pH 2.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are broken,and the unit is shaken to ensure good mixing and then gently squeezed towet the swab tip. The swab tip is rubbed over the area to be tested andbecomes purple or red if copper ion (Cu⁺²) is present.

The activator solution is prepared by dissolving 20 g sodium acetate, 10g potassiumsodium tartrates and 3 g hydroxylammonium chloride in 100 mlwater. The pH is adjusted to 2 with HCl.

EXAMPLE LV

A swab with a hollow stem is filled with 30 mg of a mixture of magnesiumnitrate (Mg(NO₃)₂) and an inert filler such as alumina in ratiosas shownin Table VI. The swab tip is first wetted with a solution containingammonium chloride (NH₄ Cl) and a little ammonia at a pH greater than 7.The area to be tested is rubbed with the swab. The swab tip is thenwetted with the second solution containing silver nitrate in dilute acid(0.01 to 0.3M HCl). If arsenate ion (AsO₄ ⁻³) is present, the swab turnsred.

EXAMPLE LVI

One crushable cartridge (labelled A) is filled with 0.5 ml of themagnesiumnitrate reagent, a solution containing magnesium nitrate(Mg(NO₃)₂), ammonium chloride (NH₄ Cl) and a little ammonia. Anotherbreakable cartridge (labelled B) is filled with 0.5 ml ofa solutioncontaining silver nitrate (Ag(NO₃)₂) in dilute acid 0.01 to 0.3 N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridge labelled A isbroken first and the unit is gently squeezed to wet the swab tip. Theswabtip is rubbed over the area to be tested. Then the breakablecartridge labelled B is broken and the unit is again gently squeezed tothoroughly wet the swab tip. If arsenate ions (AsO₄ ⁻³) are present, theswab turns red.

EXAMPLE LVII

One crushable cartridge (labelled A) is filled with 0.5 ml of a solutioncontaining magnesium nitrate (Mg(NO₃)₂) and ammonium chloride (NH₄ Cl).A second breakable cartridge (labelled B) is filled with ammonia (0.3ml). A third breakable cartridge (labelled C) is filled with 0.5 ml of asolution containing silver nitrate (Ag(NO₃)₂) in dilute acid (0.01 to0.3 N HCl).

The three cartridges are placed inside a larger cartridge having a swabtipat one end. When ready to use, the breakable cartridges labelled Aand B are broken first and the unit is gently squeezed to mix thecontents and to wet the swab tip. The swab tip is rubbed over the areato be tested. Then the breakable cartridge labelled C is broken and theunit is again gently squeezed to thoroughly wet the swab tip. Ifarsenate ions (AsO₄ ⁻³) are present, the swab turns red.

EXAMPLE LVIII

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of diluteacid (0.01-0.3 N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes black if lead (Pb⁺²) ion is present.

EXAMPLE LIX

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of diluteacid (0.01-0.3N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes black if mercury II (Hg⁺²) ion is present.

EXAMPLE LX

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of 1.0N HCl.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes black if copper II (Cu⁺²) ion is present.

EXAMPLE LXI

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of diluteacid (0.3-0.5N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes yellow if cadmium II (Cd⁺²) ion is present.

EXAMPLE LXII

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of diluteacid (0.01-0.3N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes brown if bismuth (Bi⁺³) ion is present.

EXAMPLE LXII

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of diluteacid (0.01-0.3N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes brown if tin II (Sn⁺²) ion is present and yellow if tin IV(Sn⁺⁴) ion is present.

EXAMPLE LXIV

One crushable cartridge is filled with 0.5 ml of a 7% solution of sodiumsulfide. Another breakable cartridge is filled with 0.5 ml of diluteacid (0.01-0.3N HCl).

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes yellow if selenium as the selenite ion (SeO₃ ⁻²) is present.

EXAMPLE LXV

One crushable cartridge is filled with 0.5 ml of a 7% solution ofammonium sulfide. Another breakable cartridge is filled with 0.5 ml ofan ammoniacal solution.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes black if either iron II (Fe⁺²) or iron III (Fe⁺³) ions arepresent. The black precipitate can turn brown on oxidation in air.

EXAMPLE LXVI

One crushable cartridge is filled with 0.5 ml of a 7% solution ofammonium sulfide. Another breakable cartridge is filled with 0.5 ml of0.1M NaOH. The swab tip is dyed blue or any dark color.

The two cartridges are placed inside a larger cartridge having the blueswab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing and gently squeezedtowet the swab tip. The swab tip is rubbed over the area to be testedand becomes white if aluminum ion (Al⁺³) is present.

EXAMPLE LXVII

One crushable cartridge is filled with 0.5 ml of a 7% solution ofammonium sulfide. Another breakable cartridge is filled with 0.5 ml ofconcentratedHCl. A third breakable cartridge is filled with a smallcrystal of iodine to act as a catalyst.

The three cartridges are placed inside a larger cartridge having a swabtipat one end. When ready to use, the breakable cartridges are brokenand the unit is shaken to ensure good mixing and gently squeezed to wetthe swab tip. The swab tip is rubbed over the area to be tested andbecomes yellow if arsenic ions (As⁺³ or As⁺⁵) are present.

EXAMPLE LXVIII

A swab with a hollow stem is filled with 30 mg of a mixture of coppersulfate and an inert filler such as silica in ratios as shown in TableVI.The swab tip is wetted with an activator solution containing neutralbuffersuch as 0.1M potassium phosphate at pH 7.0. The area to be testedis rubbedwith the swab. If selenium as the selenite ion (SeO₃ ⁻²) ispresent, the swab turns bluish-green.

EXAMPLE LXIX

One crushable cartridge is filled with 30 mg of copper sulfate and aninertfiller such as talc. Another breakable cartridge is filled with 0.5ml of activator solution containing a neutral buffer such as 0.1Mpotassium phosphate adjusted to pH 7.0.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand theunit is shaken to ensure good mixing. The swab tip is rubbed overthe area to be tested and becomes bluish-green if selenium as theselenite ion (SeO₃ ⁻²) is present.

EXAMPLE LXX

One crushable cartridge is filled with a 0.1% solution of copper sulfateina neutral buffer (0.1M potassium phosphate adjusted to pH 7.0). Whenready to use, the breakable cartridge is broken and the unit is gentlysqueezed to wet the swab tip. The swab tip is rubbed over the area to betested andbecomes bluish-green if selenium as the selenite ion (SeO₃ ⁻²)is present.

Although only preferred embodiments are specifically illustrated anddescribed herein, it will be appreciated that many modifications andvariations of the present invention are possible in light of the aboveteachings and within the purview of the appended claims withoutdeparting from the spirit and intended scope of the invention.

What is claimed is:
 1. A method of testing for a metal on a surface witha reagent that reacts with the metal, comprising the steps of:providinga swab stick having a stem and an absorbent ball of material at one endof the stem, wherein the absorbent ball of material is impregnated withthe reagent; contacting the impregnated absorbent ball of material withthe surface; and detecting the presence of the metal by inspecting theimpregnated ball of material for a reaction between the metal and thereagent; wherein the metal tested for is mercury.
 2. A method of testingfor a metal on a surface with a reagent that reacts with the metal,comprising the steps of:providing a swab stick having a stem and anabsorbent ball of material is impregnated with the reagent; contactingthe impregnated absorbent ball of material with the surface; anddetecting the presence of the metal by inspecting the impregnated ballof material for a reaction between the metal and the reagent; whereinthe metal tested for is arsenic.
 3. The method of claim 1 or claim 2,wherein the step of the swab stick is hollow, and the step ofimpregnating the absorbent ball includes injecting the reagent throughthe hollow stem into the center of the absorbent ball.
 4. The method ofclaim 1 or claim 2, further comprising the step of wetting the absorbentball of material with a buffer having a pH level conducive to thereaction.
 5. The method of claim 1 or claim 2, wherein the absorbentball of material is soaked with a solution comprised of the reagent, aninert filler and a buffer.
 6. The method of claim 1, wherein the reagentcomprises diphenylcarbazide or cobalt (II) thiocyanate.
 7. The method ofclaim 2, wherein the reagent comprises magnesium nitrate and ammoniumchloride.
 8. The method of claim 1 or 2, wherein the stem of the swab ishollow and the step of impregnating the absorbent ball of materialincludes injecting the reagent through the hollow stem into the centerof the absorbent ball of material.
 9. The method of claim 1 or 2,wherein the step of impregnating the absorbent ball of material includessoaking the absorbent ball of material in a solution comprised of areagent, an inert filler, and a buffer.
 10. The method of claim 9,further comprising the step of drying the absorbent ball of material.11. The method of claim 10, wherein the step of drying the absorbentball of material includes heating the absorbent ball of material. 12.The method of claim 10, wherein the step of drying the absorbent ball ofmaterial includes:freezing the absorbent ball of material; and dryingthe absorbent ball of material by lyophilization.
 13. The methodaccording to claim 1 or claim 2, wherein the reagent comprises an inertfiller.
 14. The method according to claim 13, wherein the inert filleris selected from the group including alumina, talc, gum acacia, silicicacid and mannitol.
 15. The method according to claim 13, wherein atleast some of the reagent is located within the stem.
 16. The methodaccording to claim 15, wherein the stem containing the reagent iscrimped so as to retain the reagent within the stem.
 17. The methodaccording to claim 13, wherein the ball of absorbent material is madefrom a material selected from the group consisting of cotton fibers,rayon fibers, and dacron fibers.
 18. The method according to claim 13,wherein the swab is prewashed with a solution ofethylenediaminetetra-acetic acid (EDTA).
 19. A method of testing for ametal on a surface with a reagent that reacts with the metal, comprisingthe steps of:providing a swab stick having a stem and an absorbent ballof material at one end of the stem, wherein the absorbent ball ofmaterial is impregnated with the reagent; contacting the impregnatedabsorbent ball of material with the surface; and detecting the presenceof the metal by inspecting the impregnated ball of material for areaction between the metal and the reagent; wherein the metal tested foris bismuth and the reagent comprises cinchonine and potassium iodide.20. A device for testing for a metal on a solid surface, comprising:acartridge having two ends and an absorbent ball of material mounted ateach end; at least two compartments within said cartridge wherein atleast one compartment contains a reagent that reacts with the metal andat least one of the other compartments contains an activating solution;wherein the reagent and activating solution are combined and mixedwithin the cartridge before the device is used and the substance testedfor is selected from the group consisting of lead and mercury.
 21. Thedevice of claim 20 wherein each of the at least two compartments is abreakable or squeezable cartridge.
 22. The device of claim 21 whereinthe compartment is a breakable cartridge and the breakable cartridge isglass.
 23. The device of claim 21 wherein the compartment is asqueezable cartridge and the squeezable cartridge is plastic.
 24. Thedevice of claim 23 wherein the plastic is low density polyethylene,polyallomer, butyrate tubing or polyvinyl-chloride.
 25. A device fortesting for a metal on a solid surface, comprising:a cartridge; at leasttwo compartments within said cartridge wherein at least one compartmentcontains a reagent that reacts with the metal and at least one of theother compartments contains an activating solution; and an absorbentball of material mounted at at least one end of the cartridge; whereinthe reagent and activating solution are combined and mixed within thecartridge before the device is used and the metal tested for is mercury.26. The device of claim 20 or claim 25, wherein the compartmentscomprise microencapsulation of the reagent and activating solution. 27.The device of claim 25, wherein the reagent comprises diphenylcarbazideor cobalt (II) thiocyanate.
 28. A device for testing for a metal on asolid surface, comprising:a cartridge; at least two compartments withinsaid cartridge wherein at least one compartment contains a reagent thatreacts with the metal and at least one of the other compartmentscontains an activating solution; and an absorbent ball of materialmounted at least one end of the cartridge; wherein the reagent andactivating solution are combined and mixed within the cartridge beforethe device is used and the metal tested for is arsenic and the reagentcomprises magnesium nitrate and ammonium chloride.
 29. A device fortesting for a metal on a solid surface, comprising:a cartridge; at leasttwo compartments within said cartridge wherein at least one compartmentcontains a reagent that reacts with the metal and at least one of theother compartments contains an activating solution; and an absorbentball of material mounted at at least one end of the cartridge; whereinthe reagent and activating solution are combined and mixed within thecartridge before the device is used and the metal tested for is bismuthand the reagent comprises cinchonine and potassium iodide.
 30. A testkit for testing for a metal on a solid surface, comprising:at least onecartridge; at least one crushable compartment within said cartridgecontaining a reagent that reacts with the metal; and an absorbent ballof material mounted on at least one end of the cartridge; wherein themetal tested for is lead; and further comprising a separate control tubefor dispensing sodium sulfide.
 31. The test kit of claim 30, wherein thetube comprises:a cartridge; at least one compartment within saidcartridge containing sodium sulfide; and an absorbent ball of materialmounted at one end of the cartridge.
 32. The test kit of claim 30further comprising an insert card coated in at least one area with amaterial containing the metal.
 33. The test kit of claim 31 furthercomprising an insert card coated in at least one area with a materialcontaining lead.
 34. The test kit of claim 30, further comprising anactivating solution.
 35. The test kit of claim 34, further comprising asecond crushable compartment within said cartridge for retaining theactivating solution prior to use.
 36. A device for testing for a metalon a solid surface, comprising:a hollow stem; at least one compartmentwithin said stem wherein said compartment contains a reagent that reactswith the metal in such a manner so as to give a visual indication of thereaction; an absorbent ball of material mounted at each end of the stem;and wherein said absorbent ball of material is connected to thecompartment by a passageway so that reagent in the compartment can flowto both of the absorbent balls when the compartment is opened and thereagent tested for is selected from the group consisting of lead andmercury.
 37. The device of claim 20 or 36 wherein the reagent tested foris lead.